class Turtle:

    def say(self):
        print("乌龟，爬爬爬")


class Cat:

    def say(self):
        print("小猫：喵喵喵")


class Dog:

    def say(self):
        print("小狗：汪汪汪")


# 花园中有乌龟，小猫，小狗
class Garden:
    tuple = Turtle()
    cat = Cat()
    dog = Dog()

    def say(self):
        # TODO 为什么要在前面加上 self 呢？
        self.tuple.say()
        self.cat.say()
        self.dog.say()


garden = Garden()
garden.say()
